Abstract: The air-fuel ratio feedback control is performed by using a first correction value which is determined depending on a difference between a detected air-fuel ratio (A/F) of an air-fuel mixture and a target A/F and a second correction value which is determined depending on the property of the fuel. Further, fuel property learning control is carried out to correct the first correction value and the second correction value so that an absolute value of the first correction value is not more than a threshold value, when the absolute value of the first correction value is larger than the threshold value after performing the charging with fuel.

Abstract: The air-fuel ratio feedback control is performed by using a first correction value which is determined depending on a difference between a detected air-fuel ratio (A/F) of an air-fuel mixture and a target A/F and a second correction value which is determined depending on the property of the fuel. Further, fuel property learning control is carried out to correct the first correction value and the second correction value so that an absolute value of the first correction value is not more than a threshold value, when the absolute value of the first correction value is larger than the threshold value after performing the charging with fuel.

Abstract: A fuel injection pressure at a timing at which an NOx concentration (combustion temperature) indicates a maximum value under the condition that a fuel injection timing is fixed to a first injection timing is recorded as a first NOx peak injection pressure. Similarly, a second NOx peak injection pressure is recorded under the condition that the fuel injection timing is fixed to a second injection timing. A cetane number and distillation property of fuel are determined on the basis of these NOx peak injection pressures.

Abstract: A fuel injection pressure at a timing at which an NOx concentration (combustion temperature) indicates a maximum value under the condition that a fuel injection timing is fixed to a first injection timing is recorded as a first NOx peak injection pressure. Similarly, a second NOx peak injection pressure is recorded under the condition that the fuel injection timing is fixed to a second injection timing. A cetane number and distillation property of fuel are determined on the basis of these NOx peak injection pressures.

Abstract: An object of the present invention is to determine individually and accurately an ignitability index value and an evaporativity index value of a fuel. A fuel injection valve (12) for which a fuel injection direction is set such that fuel is directed toward a cylinder wall surface (54) is included. An air-fuel ratio (a first air-fuel ratio) of an exhaust gas and a crank angular velocity (a first crank angular velocity) during combustion associated with fuel injection at a first after injection timing T1 are acquired. An air-fuel ratio (a second air-fuel ratio) of the exhaust gas and a crank angular velocity (a second crank angular velocity) during combustion associated with fuel injection at a second after injection timing T2 that is retarded from the first after injection timing T1 are acquired.

Abstract: An object of the present invention is to determine individually and accurately an ignitability index value and an evaporativity index value of a fuel. A fuel injection valve (12) for which a fuel injection direction is set such that fuel is directed toward a cylinder wall surface (54) is included. An air-fuel ratio (a first air-fuel ratio) of an exhaust gas and a crank angular velocity (a first crank angular velocity) during combustion associated with fuel injection at a first after injection timing T1 are acquired. An air-fuel ratio (a second air-fuel ratio) of the exhaust gas and a crank angular velocity (a second crank angular velocity) during combustion associated with fuel injection at a second after injection timing T2 that is retarded from the first after injection timing T1 are acquired.

Abstract: An object of the present invention is to provide a technology that enables to enhance the effect of decreasing the NOx emission achieved by an exhaust gas purification system as a whole while favorably achieving both reduction in the amount of NOx generated in an internal combustion engine by means of EGR and reduction reaction of NOx in an NOx catalyst even when a reduction process for the NOx catalyst is performed while EGR is being performed. In the invention, in the case where addition of fuel into an exhaust pipe from a fuel addition valve 28 is performed to carry out the reduction process for the NOx catalyst 20 when EGR is being performed mainly by means of a low pressure EGR passage 23, the amount of the exhaust gas passing through the NOx catalyst 20 is decreased by decreasing the amount of the exhaust gas recirculated by the low pressure EGR passage 23.

Abstract: A bypass passage is provided, which connects a portion upstream of a turbine of a supercharger in an exhaust passage to a portion close to a front end surface of exhaust gas purification in the exhaust passage, and through which at least part of exhaust gas discharged from an internal combustion engine flows. The exhaust gas discharged from the bypass passage is blown to the front end surface of the exhaust gas purification means in a lateral direction of the front end surface, whereby particulate matter deposited in the front end surface of the exhaust gas purification means is blown off.

Abstract: An object of the present invention is to provide a technology that enables to enhance the effect of decreasing the NOx emission achieved by an exhaust gas purification system as a whole while favorably achieving both reduction in the amount of NOx generated in an internal combustion engine by means of EGR and reduction reaction of NOx in an NOx catalyst even when a reduction process for the NOx catalyst is performed while EGR is being performed. In the invention, in the case where addition of fuel into an exhaust pipe from a fuel addition valve 28 is performed to carry out the reduction process for the NOx catalyst 20 when EGR is being performed mainly by means of a low pressure EGR passage 23, the amount of the exhaust gas passing through the NOx catalyst 20 is decreased by decreasing the amount of the exhaust gas recirculated by the low pressure EGR passage 23.

Abstract: A bypass passage is provided, which connects a portion upstream of a turbine of a supercharger in an exhaust passage to a portion close to a front end surface of exhaust gas purification in the exhaust passage, and through which at least part of exhaust gas discharged from an internal combustion engine flows. The exhaust gas discharged from the bypass passage is blown to the front end surface of the exhaust gas purification means in a lateral direction of the front end surface, whereby particulate matter deposited in the front end surface of the exhaust gas purification means is blown off.